Abstract: In controlling pressure in an aircraft cabin, during flight operation, an effective flow cross-sectional area of at least one outflow valve is controlled to adjust air flow exiting the cabin through the outflow valve so pressure within the cabin is controlled according to a predetermined cabin pressure control strategy. During flight operation of the aircraft, an effective flow cross-sectional area of at least one negative relief valve is controlled to adjust air flow entering the cabin through the negative relief valve so a negative differential pressure between the pressure within the aircraft cabin and an ambient pressure prevailing outside of the aircraft cabin is prevented from exceeding a predetermined threshold value. During ground operation of the aircraft, the effective flow cross-sectional area of the at least one negative relief valve is controlled to allow an equalization between pressure within the cabin and ambient pressure prevailing outside of the aircraft.

Abstract: The control system of an aircraft including at least two communication networks and a controlled device control unit connected to one of them. The system determines control commands for the device with a DAL-A quality assurance level requirement and includes a set of at least three physical units each including at least two computers, an electrical power supply and a network interface device. The electrical power supplies, and the network interface devices, are of at least three different types, the computers are of at least two different types and include operating systems of at least two different types; the computers each have a DAL-C, DAL-D or DAL-E hardware and/or software quality assurance level and at least six of the computers are configured to independently determine control commands for the device. A DAL-A hardware and software quality assurance level selection logic unit is configured to select valid control commands used by the control unit to control the device.

Abstract: In controlling pressure in an aircraft cabin, during flight operation, an effective flow cross-sectional area of at least one outflow valve is controlled to adjust air flow exiting the cabin through the outflow valve so pressure within the cabin is controlled according to a predetermined cabin pressure control strategy. During flight operation of the aircraft, an effective flow cross-sectional area of at least one negative relief valve is controlled to adjust air flow entering the cabin through the negative relief valve so a negative differential pressure between the pressure within the aircraft cabin and an ambient pressure prevailing outside of the aircraft cabin is prevented from exceeding a predetermined threshold value. During ground operation of the aircraft, the effective flow cross-sectional area of the at least one negative relief valve is controlled to allow an equalization between pressure within the cabin and ambient pressure prevailing outside of the aircraft.

Abstract: The control system of an aircraft including at least two communication networks and a controlled device control unit connected to one of them. The system determines control commands for the device with a DAL-A quality assurance level requirement and includes a set of at least three physical units each including at least two computers, an electrical power supply and a network interface device. The electrical power supplies, and the network interface devices, are of at least three different types, the computers are of at least two different types and include operating systems of at least two different types; the computers each have a DAL-C, DAL-D or DAL-E hardware and/or software quality assurance level and at least six of the computers are configured to independently determine control commands for the device. A DAL-A hardware and software quality assurance level selection logic unit is configured to select valid control commands used by the control unit to control the device.